Aluminum alloy and method for producing the same

ABSTRACT

The present disclosure provides an aluminum (Al) alloy, for general casting, and a technique for producing the same. The Al alloy includes Al, Si in the range of 5 to 13 wt %, Ti in the range of 2 to 7 wt % and B in the range of 1 to 3 wt %. According to the disclosure, a TiB 2  compound may be formed in the Al alloy, where the ratio of Ti:B may range from 2 to 2.5 wt %. The Al alloy of the disclosure has improved elasticity, and is suitable for general casting processes such as, for example, high pressure casting process.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims under 35 U.S.C. §119(a) the benefit of Korean Patent Application No. 10-2011-0125048 filed on Nov. 28, 2011, the entire contents of which are incorporated herein by reference.

BACKGROUND

(a) Technical Field

The present disclosure relates to an aluminum alloy as a casting aluminum material with high elasticity for improving the rigidity and noise, vibration, and harshness (NVH) characteristics, and a method for producing the same.

(b) Background Art

Aluminum alloys improve the properties of aluminum and displays many excellent properties, which can be varied according to the composition of the alloy. For example, high strength aluminum alloys, such as duralumin, can be made by including copper, which provides high strength characteristics to the alloy. Increasing the copper content in the alloy has the effect of increasing the strength of the alloy. For example, super duralumin is created by adding copper to the duralumin, and extra super duralumin is created by adding copper to super duralumin. Extra super duralumin is used as an aircraft material. Disadvantageously, such high strength aluminum-copper (Al—Cu_alloys such as duralumin lack the ability to resist corrosion (i.e. they are prone to corrosion). Structural aluminum alloys are typically made by adding magnesium and zinc, which confer excellent corrosion resistance properties to the alloys. Accordingly, such structural aluminum alloys are used for railway vehicles, bridges, and the like. Aluminum alloy for casting can be made by adding Si, and other metals can be mixed with Al to create alloys with a variety of other properties, such as heat-resistance and brilliance.

Aluminum alloys are largely divided into two groups: alloys for wrought material and alloys for casting material. The former group includes Al—Cu—Mg-based alloys (e.g., duralumin, super duralumin), Al—Mn-based alloys, Al—Mg—Si-based alloys, Al—Mg-based alloys, and Al—Zn—Mg-based alloys (extra super duralumin) alloys. The latter group includes Al—Cu-based alloys, Al—Si-based alloys (silumin), Al—Cu—Si-based alloys (lautal), Al—Mg-based alloys (hydronalium), Al—Cu—Mg—Si-based alloys (Y alloy), and Al—Si—Cu—Mg—Ni-based alloys (Lo.Ex alloy).

Recently, attempts have been made to generate a metal-based compound reinforced with carbon nanotubes (CNT) molded in a powder form, however, use of such a compound is limited because of its high cost. Disadvantageously, when it was applied to a casting process in a powder form, major problems were encountered with dispersion of the powder in an Al matrix. A further disadvantage results from a hypereutectic aluminum casing material that can only be made by a low pressure casting process. A further disadvantage is that processing such a material with coarse Si particles poses additional manufacturing difficulties. For example, when Si is used to increase the elasticity of a metal-based compound, or a reinforced CNT material molded in a powder form, the coarse Si particles limited the ability to improve elasticity, due in part to problems with the wetability when combined with the Al matrix, which resulted in uneven dispersion of the CNT powder when used for a continuous casting process. Additionally, the ability to work with such materials is cost prohibitive.

Accordingly, there is a need in the art for an aluminum alloy with high elasticity for use as a casting aluminum material to with improved the rigidity and noise, vibration, and harshness (NVH) characteristics.

SUMMARY OF THE DISCLOSURE

The present invention provides a continuous casting aluminum alloy for use as a high elastic continuous casting aluminum material with improved rigidity and noise, vibration, and harshness (NVH) characteristics, and a method for producing the same.

An aluminum alloy according to an exemplary embodiment of the present invention includes Al as a major component, Si in the range of 5 to 13 wt %, Ti in the range of 2 to 7 wt % and B in the range of 1 to 3 wt %, and a TiB₂ compound can be formed therein.

According to an exemplary embodiment of the present invention the aluminum alloy can include Al as a major component, Si in the range of 5 to 13 wt %, Ti in the range of 2 to 7 wt %, B in the range of 1 to 3 wt %, Fe in the range of 1.0 to 1.5 wt %, Cu in the range of 1.5 to 3.5 wt %, Mn in the range of 0.5 wt % or less (not including 0), Mg in the range of 0.3 wt % or less (not including 0), Ni in the range of 0.5 wt % or less (not including 0), Zn in the range of 1 wt % or less (not including 0) and other indispensable impurities.

According to an exemplary embodiment of the present invention the aluminum alloy can include Al as a major component, Si in the range of 5 to 13 wt %, Ti in the range of 2 to 7 wt %, B in the range of 1 to 3 wt %, Fe in the range of 0.2 wt % or less (not including 0), Cu in the range of 0.2 wt % or less (not including 0), Mn in the range of 0.1 wt % or less (not including 0), Mg in the range of 0.25 to 0.45 wt %, Ni in the range of 0.05 wt % or less (not including 0), Zn in the range of 0.1 wt % or less (not including 0) and other indispensable impurities.

The ratio of B:Ti may be 1:2˜2.5.

According to an exemplary embodiment of the present invention a method for producing the aluminum alloy includes, preparing a molten Al—Ti-based alloy comprising Ti in the range of 5 to 10 wt % and a molten Al—B-based alloy comprising B in the range of 2 to 10 wt %, and mixing the molten alloys together.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present invention will now be described in detail with reference to certain exemplary embodiments thereof illustrated the accompanying drawings which are given hereinbelow by way of illustration only, and thus are not limitative of the present invention, and wherein:

FIG. 1 is a graph comparing the TiB₂ fractions of aluminum alloys according to an exemplary embodiment of the present invention.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various preferred features illustrative of the basic principles of the invention. In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

Hereinafter reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below. While the invention will be described in conjunction with exemplary embodiments, it will be understood that the present description is not intended to limit the invention to those exemplary embodiments. On the contrary, the invention is intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

Unless specifically stated or obvious from context, as used herein, the term “about” is understood as within a range of normal tolerance in the art, for example within 2 standard deviations of the mean. “About” can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear from the context, all numerical values provided herein are modified by the term “about.”

Ranges provided herein are understood to be shorthand for all of the values within the range. For example, a range of 1 to 50 is understood to include any number, combination of numbers, or sub-range from the group consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50, as well as all intervening decimal values between the aforementioned integers such as, for example, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, and 1.9. With respect to sub-ranges, “nested sub-ranges” that extend from either end point of the range are specifically contemplated. For example, a nested sub-range of an exemplary range of 1 to 50 may comprise 1 to 10, 1 to 20, 1 to 30, and 1 to 40 in one direction, or 50 to 40, 50 to 30, 50 to 20, and 50 to 10 in the other direction.

It is understood that the term “vehicle” or “vehicular” or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g., fuels derived from resources other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more sources of power, for example both gasoline-powered and electric-powered vehicles.

Hereinafter, an aluminum alloy and a method for producing the same according to the preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

The aluminum alloy according to the present invention has a composition comprising: Al as a major component, Si in the range of 5˜13 wt %, Ti in the range of 2˜7 wt % and B in the range of 1˜3 wt % so as to form a TiB₂ compound.

The present invention provides a high elastic casting aluminum material with improved rigidity and NVH characteristic. Conventionally, when only using Si for high elasticity, there were problems with restricted elasticity improvement and processability as a result of the coarse Si particles. A metal-based compound or a reinforced phase such as CNT was molded with a powder form, but it had a very limited usefulness as a result of the fact that the material was prohibitively expensive, and because of problems with the wetability of an Al matrix and the resulting dispersion problems that arose when the material was applied to a continuous casting process as the powder form.

The present invention implements a boride compound to provide an aluminum alloy having high elasticity, which can maximize improvement of the uniformity and elasticity of the alloy. In particular, an exemplary embodiment of the invention enables the use of a general casting process such as, for example, a high pressure casting process, to be used.

The aluminum alloy of the present invention makes up a basic alloy system by limiting the Si content to the range of 5 to 13 wt % for embodying the improvements of both castability and elasticity, and the Ti content to the range of 2 to 7 wt % and the B content to the range of 1 to 3 wt % for forming the boride compound (TiB₂: 541 GPa), which is the most effective compound to improve the elasticity.

According to another exemplary embodiment of the invention, in addition to the aluminum alloy, an alloy structure prepared by adding Ti in the range of 2 to 7 wt % and B in the range of 1 to 3 wt % to the conventional ADCl2, AC4CH, AC2B, which are the most representative alloy systems for high pressure casting and gravity/low pressure casting, can also obtain a similar result with improved elasticity.

According to an exemplary embodiment of the invention, in order to maximize boride production in the material, the ratio of Ti and B is controlled to the range of 2˜2.5. In order to control the ratio of Ti and B, a powder-type is not injected; rather, the ration is formed naturally in a molten metal by using master aluminum alloys of Al-(in the range of 5 to 10 wt %) Ti and Al-(in the range of 2 to 10 wt %) B, so as to secure the material uniformity.

Through this aluminum alloy, the elasticity and other properties (such as, e.g., strength, wear-resistance, processability and the like) are improved by uniform distribution of the micro-TiB₂ phase and by maximization of boride production.

Conventionally, the general elasticity coefficient of an aluminum alloy is 75 GPa. In contrast, the elasticity coefficient of the 1Ti-1B (micro-TiB₂ 1.45%) aluminum alloy of an exemplary embodiment of the present invention is significantly increased to 92.8 GPa. Further, in case of 2.3Ti-1B (micro-TiB₂ 3.34%), the elasticity coefficient is increased to 103.8 GPa.

Additionally, a hypereutectic aluminum, which is a representative alloy used in the conventional art as a mass production material, is restricted to low pressure casting methods. However, the aluminum alloy of an exemplary embodiment of the present invention has no such restriction on the casting process.

In an exemplary embodiment, the aluminum alloy of the present invention may have a composition comprising: Al as a major component, Si in the range of 5 to 13 wt %, Ti in the range of 2 to 7 wt %, B in the range of 1 to 3 wt %, Fe in the range of 1.0 to 1.5 wt %, Cu in the range of 1.5 to 3.5 wt %, Mn in the range of 0.5 wt % or less (not including 0), Mg in the range of 0.3 wt % or less (not including 0), Ni in the range of 0.5 wt % or less (not including 0), Zn in the range of 1 wt % or less (not including 0) and other indispensable impurities.

Further, as another exemplary embodiment, the aluminum alloy may have a composition comprising: Al as a major component, Si in the range of 5 to 13 wt %, Ti in the range of 2 to 7 wt %, B in the range of 1 to 3 wt %, Fe in the range of 0.2 wt % or less (not including 0), Cu in the range of 0.2 wt % or less (not including 0), Mn in the range of 0.1 wt % or less (not including 0), Mg in the range of 0.25 to 0.45 wt %, Ni in the range of 0.05 wt % or less (not including 0), Zn in the range of 0.1 wt % or less (not including 0) and other indispensable impurities.

Table 1 is a table comparing chemical compositions of the conventional aluminum alloy of the Comparative Example and the aluminum alloy according to one exemplary embodiment of the present invention.

TABLE 1 Si Fe Cu Mn Mg Ni Zn Ti B Al Compar- 9.6~12 1.3 1.5~3.5 0.5 0.3 0.5 1 <0-3  — Bal. ative Example Present   5~13% — — — — — — 2~7 1~3 Bal. Inven- tion Example 9.6~12 1.3 1.5~3.5 0.5 0.3 0.5 1 2~7 1~3 Bal.

As shown in Table 1, the aluminum alloy of the present invention has a composition comprising: Al as a major component, Si in the range of 5 to 13 wt %, Ti in the range of 2 to 7 wt % and B in the range of 1 to 3 wt %, so as to form a TiB₂ compound therein, and as a result, the general elasticity coefficient of an aluminum alloy is 75 GPa, while the elasticity coefficient of the 1Ti-1B (micro-TiB₂ 1.45%) aluminum alloy of the present invention significantly increased to 92.8 GPa.

On the other hand, the ratio of B:Ti may be 1:2 to 2.5 because the TiB₂ production increases as the Ti/B ratio is increased.

On the other hand, in the method for producing the aluminum alloy, the aluminum alloy can be prepared by mixing a molten Al—Ti-based alloy comprising Ti in the range of 5 to 10 wt % and a molten Al—B-based alloy comprising B in the range of 2 to 10 wt % together because in order to control the ratio of Ti and B, a powder-type is not injected, but rather a natural formation in a molten metal is induced using master aluminum alloys of Al—(in the range of 5 to 10 wt %) Ti and Al—(in the range of 2 to 10 wt %) B, so as to secure the material uniformity.

Table 2 represents the comparison of the phase fraction according to the multi-element phase equilibrium calculation.

TABLE 2 Ti:B = 1:1 Ti:B = x:1 Alloy TiB₂ Alloy TiB₂ B 1 wt % Al—1Ti—1B 1.45 Al—2.3Ti—1B 3.21 Content 2 wt % Al—2Ti—2B 2.9 Al—4.5Ti—2B 6.3 3 wt % Al—3Ti—3B 4.36 Al—6.7Ti—3B 9.64

As shown Table 2, it is confirmed that the composition containing the TiB₂ single phase was changed by increasing the B content, and the TiB₂ production increased by increasing the Ti/B ratio. Through this TiB₂ increase, the elasticity characteristics of the resulting material can be significantly improved.

FIG. 1 is a graph comparing the TiB₂ fractions of aluminum alloys according to one exemplary embodiment of the present invention, and it is confirmed that the phase fraction of TiB₂ increased by increasing the contents of B and Ti (TiB₂ is a part expressed as MB2 at the graph).

According to the aluminum alloy and the method for producing the same consisting of the structure described above, the elasticity and other properties (such as, e.g., strength, wear-resistance, processability and the like) of the aluminum alloy are improved by uniform distribution of the micro-TiB₂ phase and by maximization of boride production.

While the invention will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention to those exemplary embodiments. On the contrary, the invention is intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims. 

What is claimed is:
 1. An aluminum alloy, comprising: Al, Si in the range of 5 to 13 wt %, Ti in the range of 2 to 7 wt %, and B in the range of 1 to 3 wt %.
 2. The aluminum alloy of claim 1, wherein a TiB₂ compound is formed therein.
 3. The aluminum alloy of claim 1, further comprising: Fe in the range of 1.0 to 1.5 wt %, Cu in the range of 1.5 to 3.5 wt %, Mn in the range of 0.5 wt % or less, Mg in the range of 0.3 wt % or less, Ni in the range of 0.5 wt % or less, and Zn in the range of 1 wt % or less.
 4. The aluminum alloy of claim 3, wherein the amount of Mg, Ni, and Zn is more than 0 wt %.
 5. The aluminum alloy of claim 1, further comprising Fe in the range of 0.2 wt % or less, Cu in the range of 0.2 wt % or less, Mn in the range of 0.1 wt % or less, Mg in the range of 0.25 to 0.45 wt %, Ni in the range of 0.05 wt % or less, and Zn in the range of 0.1 wt % or less.
 6. The aluminum alloy of claim 5, wherein the amount of Fe, Cu, Mn, Mg, Ni, and Zn is more than 0 wt %.
 7. The aluminum alloy of claim 1, wherein the ratio of B:Ti is 1:2˜2.5.
 8. The aluminum alloy of claim 7, wherein the ratio of B:Ti is 1:2.
 9. The aluminum alloy of claim 7, wherein the ratio of B:Ti is 1:2.1.
 10. The aluminum alloy of claim 7, wherein the ratio of B:Ti is 1:2.2.
 11. The aluminum alloy of claim 7, wherein the ratio of B:Ti is 1:2.3.
 12. The aluminum alloy of claim 7, wherein the ratio of B:Ti is 1:2.4.
 13. The aluminum alloy of claim 7, wherein the ratio of B:Ti is 1:2.5.
 14. A method for producing the aluminum alloy of claim 1, comprising: mixing a molten Al—Ti-based alloy comprising Ti in the range of 5 to 10 wt % and a molten Al—B-based alloy comprising B in the range of 2 to 10 wt % together, thereby forming the aluminum alloy.
 15. The method of claim 14, wherein a TiB₂ compound is formed in the aluminum alloy.
 16. The method of claim 14, wherein the ratio of B:Ti is 1:2.
 17. The method of claim 14, wherein the ratio of B:Ti is 1:2.1.
 18. The method of claim 14, wherein the ratio of B:Ti is 1:2.2.
 19. The method of claim 14, wherein the ratio of B:Ti is 1:2.3.
 20. The method of claim 14, wherein the ratio of B:Ti is 1:2.4.
 21. The method of claim 14, wherein the ratio of B:Ti is 1:2.5. 